docs: def parse_port_from_tensorboard_output(tensorboard_output: str) -> int:
      """
      Parse tensorboard port from its outputted message.
  
      :param tensorboard_output: Output message of Tensorboard
      in format TensorBoard 1.8.0 at http://martin-VirtualBox:36869
      :return: Returns the port TensorBoard is listening on.
      :raise UnexpectedOutputError
      """
      search = re.search("at http://[^:]+:([0-9]+)", tensorboard_output)
      if search is not None:
          port = search.group(1)
          return int(port)
      else:
          raise UnexpectedOutputError(tensorboard_output, "Address and port where Tensorboard has started,"
                                                          " e.g. TensorBoard 1.8.0 at http://martin-VirtualBox:36869")